Fast pyrolysis of bio-mass involves rapidly heating solid bio-mass to a temperature of 400° C. to 600° C. in reducing conditions so that it forms an oil. This is typically done in a fluidized bed, where approximately 60% of the original biomass can be recovered as oil. The pyrolysis is endothermic in nature, and the energy required is typically obtained by heating the fluidized bed indirectly, using electrical heating elements.
The source of heat for heating the fluidised bed is sand which is heated using electrical heating elements to provide the energy for the endothermic reaction. Electrical energy is continuously required in order to maintain the pyrolysis reaction.
In order to reduce the electrical energy demand, char produced by the pyrolysis of the bio-mass is recycled as a fuel to the pyrolysis reaction where it is combusted to provide some of the energy required to maintain the pyrolysis temperature, however, this is done at the expense of the char being lost.
The inventors have thus identified a need for a more efficient pyrolysis apparatus for the pyrolysis of bio-mass while reducing the need for an external energy source and possibly allowing for some or all of the char thus produced to be retained for alternative use rather than as a fuel to the pyrolysis.